I just bought the book, but found myself stuck at chapter 2.3. I'd typed up the Hello World example, but then realised that the book didn't offer any hints about where to save the helloworld.html file, nor how to run it. In fact, I realised that the book didn't seem to actually explain how to get Sencha running under Windows (or in fact under any OS at all). How frustrating!

Maybe I'm not the target audience, but it seems to me that there's an awful lot missing between chapters 2.2 and 2.3.

Anyway, I've put up a web page that explains what I did to get everything running on a Windows 7 PC. Hopefully, this will help someone.